胃的奇妙防護罩：為什麼它不會消化自己？
The Stomach's Marvelous Shield: Why Doesn't It Digest Itself?
「小欣老師，我們的胃是不是很厲害？」小惠好奇地問，一邊摸著自己的肚子。「當然囉，小惠！胃是個超棒的消化工廠，每天努力把食物變成身體可以吸收的養分。」小欣老師微笑著回答。
"Teacher Star, isn't our stomach amazing?" Leona asked curiously, patting her tummy. "Of course, Leona! The stomach is an incredible digestive factory, working hard every day to turn food into nutrients our body can absorb," Teacher Star replied with a smile.
小欣老師接著解釋：「胃會分泌一種超級強大的『胃液』，裡面有兩種秘密武器：一個是像閃電一樣的鹽酸，負責殺菌和初步分解食物；另一個是像小剪刀的胃蛋白酶，專門把蛋白質大分子剪成小分子。它們加起來，連金屬都會怕！」
Teacher Star continued to explain, "The stomach secretes a super powerful 'gastric juice' containing two secret weapons: one is hydrochloric acid, like lightning, responsible for killing bacteria and initially breaking down food; the other is pepsin, like tiny scissors, specifically designed to cut large protein molecules into smaller ones. Together, they are so strong that even metal would fear them!"
小惠聽得目瞪口呆：「哇！這麼厲害的胃液，那為什麼我們的胃不會被它自己消化掉呢？它不是也是蛋白質做的嗎？這真是個大謎團！」她不解地撓了撓頭。
Leona listened with wide-eyed astonishment: "Wow! Such powerful gastric juice, then why doesn't our stomach digest itself? Isn't it also made of protein? This is a huge mystery!" She scratched her head in confusion.
小欣老師神秘地眨了眨眼：「哈！這就是身體的奇妙之處了！其實，我們的胃有一個超級高級的『防護罩』。想像一下，胃就像穿著一件厚厚的防水防酸雨衣！」
Teacher Star winked mysteriously: "Ha! That's the wonder of the human body! Actually, our stomach has a super advanced 'protective shield.' Imagine, the stomach is like wearing a thick, waterproof, acid-proof raincoat!"
「這個『雨衣』就是胃內壁分泌的一層厚厚的『黏液』。它就像一道堅固的城牆，把強酸的胃液和我們的胃壁隔開，不讓它們直接接觸。沒有這層黏液，我們的胃就危險了！」小欣老師解釋道。
"This 'raincoat' is a thick layer of 'mucus' secreted by the inner lining of the stomach. It acts like a strong city wall, separating the highly acidic gastric juice from our stomach wall, preventing direct contact. Without this mucus layer, our stomach would be in danger!" Teacher Star explained.
「原來如此！」小惠恍然大悟。「那胃蛋白酶呢？它不會在不該作用的地方就開始剪食物嗎？」小惠又提出了新問題。
"I see!" Leona exclaimed, suddenly understanding. "What about pepsin? Doesn't it start cutting food where it shouldn't?" Leona posed another question.
「問得好！」小欣老師讚賞道。「胃蛋白酶其實很聰明，它剛被分泌出來的時候，是處於『不活化狀態』，我們叫它『胃蛋白酶原』。只有當它遇到胃酸後，才會像超級英雄變身一樣，變成真正有威力的胃蛋白酶！」
"Good question!" Teacher Star praised. "Pepsin is actually very clever. When it's first secreted, it's in an 'inactive state,' which we call 'pepsinogen.' Only when it encounters gastric acid does it transform, like a superhero, into the truly powerful pepsin!"
「哇，身體真是太聰明了！」小惠驚呼。小欣老師點點頭，語氣變得有些嚴肅：「沒錯，但如果這層黏液防護罩被破壞了，胃液就會直接接觸胃壁，那就會造成『胃潰瘍』，讓胃壁受傷、疼痛，甚至可能出血。」
"Wow, the body is truly intelligent!" Leona exclaimed. Teacher Star nodded, his tone becoming a bit more serious: "Indeed, but if this protective mucus shield is damaged, gastric juice will directly contact the stomach wall, leading to 'gastric ulcers.' This causes the stomach wall to be injured, painful, and potentially even bleed."
小惠聽了有些害怕：「那要怎麼辦呢？為什麼防護罩會被破壞？」小欣老師解釋：「長期吃某些止痛藥、感染一種叫幽門螺旋桿菌的細菌、或是壓力太大、飲食不正常，都可能讓這層防護變弱，甚至破洞。」
Leona felt a little scared: "Then what should we do? Why would the shield break?" Teacher Star explained: "Long-term use of certain painkillers, infection with a bacterium called H. pylori, or excessive stress and irregular diet can all weaken this protective layer, or even cause holes in it."
小欣老師最後總結道：「所以你看，我們的身體設計得有多麼精巧！胃酸在對的地方、對的時間發揮作用，酵素也被巧妙地『包裝』，加上那層像城牆一樣的黏液。這些精密的協同合作，才讓我們能安心享受美食，而不用擔心胃會消化自己喔！」
Teacher Star concluded, "So you see how exquisitely our body is designed! Gastric acid works in the right place, at the right time, enzymes are cleverly 'packaged,' and there's that mucus layer like a city wall. It's this precise teamwork that allows us to enjoy delicious food without worrying about our stomach digesting itself!"